The present invention relates to hot-melt adhesives and, more particularly, to the recycling of hot-melt adhesives and similar thermoplastic materials commonly used in electric hot-melt adhesive dispensing guns.
Hot-melt adhesive dispensing guns, commonly known as glue guns, have achieved widespread use in the consumer market where they are used to effect common household repairs. The guns typically include a body portion having an internal electric heater and an integral handle that is grasped by the user. Solid adhesive or caulking materials in the form of short, cylindrical sticks (typically two or four inches in length and 0.5 inches in diameter) are loaded into the gun through an entry port and melted by the heater for discharge through a nozzle. A typical gun has the internal capacity to accommodate two to four two-inch sticks in a molten state for discharge through the nozzle. In order to change from one type of thermoplastic material, e.g., from a traditional adhesive to a caulking material, the contents of the gun must first be purged. This can be accomplished by loading the gun with two or three sticks of the desired material and continuously discharging the hot contents of the gun until the internal passages and cavities of the gun are purged of the former material and filled with the desired material. As can be appreciated, frequent changeover from one material to another is both time consuming and wasteful. The inconvenience associated with a changeover limits the variety of materials that can be used with traditional hot-melt glue guns. While hot-melt adhesives can be fabricated in different compositions for different purposes, for example, adhesives for adhering cloth, stone, metal, glass, etc., and caulks in different colors or compositions, the waste associated with the need to purge the prior contents of the gun represents a practical limit of the ability to market a wide variety of adhesive and caulk compositions.